1. Field of the Invention
The present invention relates to a method of processing a moving picture displayed on a liquid crystal display, a moving picture processing apparatus, and a computer program product therefore.
2. Description of the Related Art
In recent years, liquid crystal displays come to be utilized in a wide variety of fields, for example, as displays for personal computers (PC), notebook type PCs, and televisions. And opportunities to view moving pictures on liquid crystal displays have been increasing.
On the liquid crystal display which response speed is not sufficiently high, however, image degradation such as blurring and afterimage occurs at the moving picture display. In general a refresh rate of the liquid crystal display is 60 Hz (hertz). Hence, a response speed of equal to or less than 16.7 milliseconds (ms) is desirable for an appropriate display of moving pictures.
On recent liquid crystal displays, the response speed required for the transition between digital values (from 0 gray-scale level to 255 gray-scale level, or from 255 gray-scale level to 0 gray-scale level on a 256-gray-scale level liquid crystal display) is equal to or faster than 16.7 ms. However, the response speed for a transition between intermediate gray-scale levels is equal to or slower than 16.7 ms.
In general, since moving pictures have a large number of intermediate gray-scale levels, the insufficient response speed for the transition between intermediate gray-scale levels incurs degradation of moving picture quality. Hence, further improvement in the response speed is required.
To achieve higher response speed in liquid crystal displays, various efforts have been made, for example, development of novel materials for liquid crystal with higher response speed, and improvement of driving method of liquid crystal displays fabricated with the conventional liquid crystal materials. Such novel materials for liquid crystal are, for example, smectic ferroelectric liquid crystal and antiferroelectric liquid crystal.
There still remain various problems to be solved, for example, an image sticking caused by the effect of spontaneous polarization of the liquid crystal material, and sensitivity of liquid crystal orientation towards pressure or the like.
On the other hand, some methods to improve the response speed of the liquid crystal display through the improvement of driving method of liquid crystal display fabricated with the conventional liquid crystal material. For example, 2001 SID International Symposium Digest of Technical Papers/Volume XXXII/ISSN-0001-966×, p. 488 discloses a method to increase gray-scale level as appropriate at the writing of the gray-scale level into the liquid crystal display so as to properly handle the change of the gray-scale level on the display.
Alternatively, edge enhancement can be applied to increase the spatial sharpness of pictures. The edge enhancement is a technique to increase the sharpness of the picture by amplifying a spatial derivative (generally, the spatial derivative is a difference between pixel values of adjacent pixels, since the picture is consisted from non-continuous data) of the picture.
The edge enhancement in general, however, increases the sharpness of the picture depending only on the information on spatial direction of the picture. Hence, the effect of the edge enhancement is insufficient when applied on the moving picture. More specifically, when the viewer focuses his/her attention on an area with a motion in the moving picture, the point of regard moves toward the direction of motion, and an apparent contrast to the viewer is decreased.
A general image capturing system captures the image by integrating light supplied during a predetermined time period. Hence, when a moving object is a target of image capture, the integration is performed on a spatially shifted position. Thus, so-called “blurring at image capture” occurs to decrease the contrast of the moving picture compared with the contrast of the still picture.
Further in a liquid crystal apparatus, since the moving picture is continuously displayed as a still picture for one frame period, so-called “hold blurring” occurs to decrease the contrast of the moving picture.
Thus, when the general edge enhancement is applied on a moving picture including a still area and a moving area, apparent sharpness is different in the still area and the moving area. Hence, subjective image quality is not improved as expected.